Materials Literature
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The notion of quasi dislocations is used to describe the sources of internal stresses in a nonuniformly magnetized body which is otherwise perfect. Energy densities and interaction energies with other defects are derived in the same formalism. The distortion tensor (strains and rotations) is calculated in the case of…
The reaction of a modulated beam of molecular oxygen with the prism plane of pyrolytic graphite was investigated. Diffusional processes in the bulk dominated the response of the emission rates of CO and CO2. The phase lags of these products relative to the impinging reactant beam indicated that the surface reactions w…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTOrganometallic chalcogen complexes. XXV. Structural and magnetic studies of Co3(h5-C5H5)3(CO)(S), Co3(h5-C5H5)3S2, and the oxidized monocation, [Co3(h5-C5H5)3S2]+. Sensitivity of the geometry of a triangular metal cluster system to antibonding electronsP. Douglas Frisch and…
Abstract The results of kinetic investigations with pure chorismate mutase-prephenate dehydratase from Escherichia coli K-12 were as follows: a pH optimum of 7.3 for the mutase activity, a Km of 0.045 mm for chorismate, and a Km of 1.0 mm for prephenate. l-Phenylalanine inhibited both the mutase and the dehydratase ac…
A review of measured breakdown properties in insulating films and of electronic theories of breakdown shows both theoretical and experimental inconsistencies. A theory is proposed in which electronic breakdown is caused by local chance events, such as a succession of avalanches at one spot. Successive avalanches susta…
We have developed a set of differential equations which describe the hydrodynamics of a conducting liquid crystal subjected to external electromagnetic fields. The mechanical forces resulting from the interaction of the fields with the liquid are expressed as operations on the Maxwell stress tensor. The use of this de…
Luminescence and related optical properties of Er 3+ and Yb 3+ -doped YF 3 , Y 3 OC 7 and YOCl phosphors are precisely and extensively measured in the range from 4.2 K to room temperature, in order to investigate the mechanism and controlling factors of infrared-to-visible conversion. It is concluded that the red lumi…
The magnetic anisotropy of R2Co17 and R2Co17−xTx compounds with R=Y, Ce, Pr, Nd, Th and T=Mn, Fe has been investigated. The directions of easy magnetization were determined by x-ray studies on oriented powders. The several R2Co17 compounds, except for Ce2Co17, have an easy basal plane; the behavior of Ce2Co17 could no…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSwelling, Crazing, and Cracking of an Aromatic Copolyether-Sulfone in Organic MediaR. P. Kambour, E. E. Romagosa, and C. L. GrunerCite this: Macromolecules 1972, 5, 4, 335–340Publication Date (Print):July 1, 1972Publication History Published online1 May 2002Published inissue…
The phenomenon of frequency-modulation (F M) sidebands induced with rf fields in the M\"ossbauer spectra of ferromagnetic materials is considered in detail. The general expression for the M\"ossbauer transition probability in the presence of rf acoustic vibrations is given and is derived on a quantum basis. The experi…
Abstract Alkoxides of transition metals, such as Fe, Ti, Nb, and Zr, were found to react with atmospheric carbon dioxide in benzene solution at 30°C. The measurement of CO2 volume absorbed and IR data suggest that transition metal alkoxides are partially carbonated.
It is demonstrated that argon-ion beams are effective in drilling holes in diamonds. Truncated conical holes were made with basal diameters as small as ∼0.375 mm and tapering to ∼0.05-mm diameter at the top. Larger holes with diameters at the two surfaces of 1.45 and 2.26 mm were milled through a 1.58-mm-thick diamond…
Abstract The thermal decomposition reactions of metal oxalato complexes in the solid state were studied by the TG and DSC methods. The results from TG indicated that the thermal stability of the anhydrous complex decreases approximately with the increase in the electron affinity of the central metal ion. From DSC, the…
Room‐temperature strengths are reported for titania and aluminum silicate in various biaxial stress states. Results are compared with failure criteria based on either energy or internal‐friction concepts. In general, more complete and reliable data for ceramic materials are needed before specific failure criteria can…
Abstract It has been demonstrated that the poly(vinyl fluoride) film can be fluorinated by exposing the polymer to an environment of fluorine under atmospheric pressure and at ambient temperature. Fluorine content, infrared spectra, thermal properties, and solubilities in the polar solvents were investigated for the f…
The rate of decomposition of PVDC is sensitive to differences in the method of preparation of the polymer. Polymers prepared by mass polymerization of very pure monomer were most stable. Emulsion polymerized PVDC degraded the fastest. The activation energy for the latter was 34.4 kcal/mole. Over the range of 130°–190°…
Ultrasonic interferometry was used to measure elastic‐wave velocities and moduli in six Na 2 O‐TiO 2 ‐SiO 2 glasses; three glasses contained 20 mol% TiO 2 and three 25 mol% TiO 2 . The elastic moduli and their pressure derivatives varied systematically with the SiO 2 /Na 2 O molar ratio of the glasses. In the group of…
Estimates have been made from electrode potential measurements of the composition and stability constants of the complexes formed by tin with citric, malic, oxalic and tartaric acids in solutions of the concentration range appropriate to canned fruits. The stability constants suggested are highest for oxalic acid, smu…
A neutron diffraction study of orthorhombic L‐histidine, C 6 H 9 N 3 O 2 , has been carried out. The structure belongs to space group P2 1 2 1 2 1 , with four molecules per unit cell. Cell parameters are: a = 5.175 (5) Å, b = 7.315 (8) Å and c = 18.75 (2) Å. A total of 618 unique reflections were used in the least‐squ…
β eucryptite, Li 2 O · Al 2 O 3 · 2SiO 2 , has a high-quartz-like structure. It crystallizes in the space group P 6 2 22. X-ray diffraction photographs of single crystals show, besides the main reflections of a high-quartz-like subcell, superstructure reflections which lead to doubling of the lattice constants of the…